ALAN L. BALCH

Professor

Email: albalch@ucdavis.edu

Inorganic Chemistry

B.A., Cornell University, 1962.
Leeds and Northrop Predoctoral Fellow, 1962-63.
NSF Predoctoral Fellow, 1963-66.
M.A.; Ph.D., Harvard University, 1965; 1967.
Appointed to faculty, UC Los Angeles, 1967-1970.
Appointed to faculty, UC Davis, 1970-,
NSF Creativity Award, 1989.
Editorial Board, INORGANIC CHEMISTRY, 1989-1991.
Metallobiochemistry Study Section NIH, 1990-94; Chair, 1992-94

Research Interests

Synthetic and structural chemistry of transition metals, catalysis, polynuclear metal complexes, metalloporphyrins, fullerene chemistry, bioinorganic chemistry.

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OXIDATION MECHANISMS. The abundant supply molecular oxygen in our environment makes oxidative processes commonplace in biological systems, in the degradation of man-made materials, and in the chemical industry. We are concerned with establishing the intimate details of how oxidations with dioxygen occur. Many of these involve metal ions as catalysts. Past work in our laboratory has demonstrated the importance of peroxo-bridged iron porphyrin dimers, ferryl (Fe^IVO²⁺) porphyrins and complexes of alkyl peroxides in these processes. Current work is focused on the insertion of dioxygen into metal-carbon bonds (both in porphyrin and non- porphyrin complexes), the formation of M-O-O-R complexes, and the mechanism of decomposition of these hydroperoxide complexes.

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HEME DEGRADATION. Under normal and abnormal metabolic processes the porphyrin ligand in heme enzymes can undergo covalent modification that leads to enzyme inactivation and heme degradation. We are concerned with unraveling the mechanisms by which such heme modification occurs. Current work is focused on oxidative heme cleavage which eventually produces carbon monoxide, bilirubin, and free iron ion. This process occurs in the action of the enzyme heme oxygenase which has free heme as substrate and molecular oxygen as oxidant. We are actively examining a model system for this process and are studying the structure and reactivity of iron complexes of important intermediates (complexes of meso-hydroxylated hemes and of biliverdin for example) in the process.

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FULLERENE CHEMISTRY AND MATERIALS. We are involved in studies of the structure and chemical reactivity of the fullerenes (C₆₀, C₇₀, C₈₄) and their derivatives. We have utilized the reversible binding of Vaska's complex, Ir(CO)CI(PPh₃)₂, to fullerenes as a structural probe. Such adduct formation produces ordered single crystals suitable for X-ray diffraction and has yielded the first three dimensional metric structural information on the higher fullerenes C₇₀ and C₈₄. Current research plans focus on obtaining fullerene based materials that display useful properties. Fullerene epoxides have been shown to undergo cathodic electropoly-merization to form tough, redox active films that may be of technological importance in battery, microsensor, and microelectronic devices. Efforts to obtain other fullerene derivatives suitable for polymer formation are under active investigation. The chemical behavior of fullerene fragments (curved organic hydrocarbons) is also under study.

SUPRAMOLECULAR CHEMISTRY. We are concerned with identification of the factors involved in interactions between molecules to form multimolecular aggregates. Extensive efforts are underway to identify new structural motifs in molecular solids that account for attractive interactions between unlike molecules. We are exploring the ability of unlike molecules to co-crystallize as a means of preparing complex supramolecular assemblies. Examples include solids comprised of (1) Pd₆Cl₁₂ and aromatic hydrocarbons, (2) fullerenes and porphyrins, (3) gold(I) complexes and organic electron acceptors.

Publications

Koerner, R., M.M. Olmstead, A. Ozarowski, S.L. Phillips, P.M. Van Calcar, K. Winkler, and A.L. Balch. 1998. Possible intermediates in biological metalloporphyrin oxidative degradation. Nickel, copper, and cobalt complexes of octaethylformybiliverdin and their conversion to a verdoheme. J. Am. Chem. Soc., 120, 1274-1284.

Vickery, J.C., M.M. Olmstead, E.Y. Fung, and A.L. Balch. 1997. Solvent-stimulated luminescence from the supramolecular aggregation of a trinuclear gold(I) complex that displays extensive intermolecular Au…Au interactions. Angew. Chem. Int. Ed. Engl., 36, 1179-1181.

Forkey, D.M., S. Attar, B.C. Noll, R. Koerner, M.M. Olmstead, and A.L. Balch. 1997. Crystallographic characterization of the molecular structure and solid state packing of the fullerene-shaped hydrocarbon C36H12. J. Am. Chem. Soc., 119, 5766-5767.

Winkler, K., D.A. Costa, W.R. Fawcett, and A.L. Balch. 1997. Alteration of the electrochemistry of fullerene C60 in the presence of dioxygen: Formation of a redox-active polymeric film. Adv. Mater., 9, 153-156.

Attar, S., A.L. Balch, P.M. Van Calcar, and K. Winkler. 1997. Electron transfer behavior and solid state structures of the helical cobalt complexes of the open-chain tetrapyrrole ligand, octaethylbilindione. J. Am. Chem. Soc., 119, 3317-3323.

Olmstead, M.M., A.S. Ginwalla, B.C. Noll, D.S. Tinti, and A.L. Balch. 1996. Supramolecular aggregation of Pd6Cl12, a cluster of comparable size to a fullerene, with aromatic donors and with C60. J. Am. Chem. Soc., 118(33), 7737-7745.

Balch, A.L., L. Hao, and M.M. Olmstead. 1996. Patterns of multiple additions to fullerene C70: Isolation and structural characterization of [C70{Pt(PPh3)2}4]. Angew. Chem. Int. Ed. Engl., 35(2), 188-190.